1. Field of the Invention
This invention relates to methods for medical treatment of pathological conditions. More particularly, the invention relates to methods for using acoustic shock waves to treat a variety of pathological conditions.
2. Description of Related Art
The use of energy wave forms for medical treatment of various bone pathologies is known in the art. For example, U.S. Pat. No. 4,530,360, issued on Jul. 23, 1985 to Duarte, teaches the use of ultrasound transducers, in direct contact with the skin of the patient, for transmitting ultrasound pulses to the site of the bone defect. Duarte teaches a nominal ultrasound frequency of 1.3 to 2.0 MHz, a pulse width range of 10 to 2000 microseconds, and a pulse rate varying between 100 and 1000 Hz Duarte maintains the ultrasound power level below 100 milliwatts per square centimeter, with treatments lasting no more than 20 minutes per day. Other devices utilize piezoelectric materials fastened adjacent to the pathological site on the patient""s limb to produce ultrasonic energy in the vicinity of the bone pathology for administering therapy. Examples of such prior art references include U.S. Pat. Nos. 5,211,160, 5,259,384, and 5,309,898.
Clinicians have also utilized shock waves to treat various pathologies. Early approaches of using shock waves for medical treatment required immersing the patient in water and directing a shock wave, generated by an underwater spark discharge, at a solid site to be treated, such as a bone or kidney stone. When the shock wave hits the solid site, a liberation of energy from the change of acoustic impedance from water to the solid site produces pressure in the immediate vicinity of the site. For example, U.S. Pat. No. 4,905,671 to Senge et al., issued on Mar. 6, 1990, teaches a method applying acoustic shock waves to induce bone formation. Senge et al. teaches that the acoustical sound waves utilized by Duarte (and similar references) for treatment of bone have a generally damped sinusoidal wave form centered on ambient pressure. More specifically, Senge et al. teaches that the pressure of an acoustical sound wave utilized by Duarte rises regularly to a maximum value above ambient, falls regularly through ambient and on to a minimum value below ambient in a continued oscillation above and below ambient until complete damping occurs. Portions of the wave above ambient represent acoustic compression, while portions-below ambient represent acoustic tension.
Senge et al. differentiates an idealized shock wave from the acoustic sound wave of Duarte as having a single pressure spike having a very steep onset, a more gradual relaxation, and virtually no oscillation to produce acoustic tension. Furthermore, Senge et al. teaches that the absence of extensive tension wave components allows the shock wave form to pass through soft tissue to cause controlled trauma within a designated bone sight. Senge et al. also teaches the minimization of the amplitude and extent of tension components in the wave forms for the treatment of bone.
Senge et al. utilizes the extremely short rise time of the shock wave to create high compression zones within bone tissue to cause reactions of the microcompartments of the bone. Senge et al. purports that such reactions cause the formation of hematomas within bone, which in turn, induce the formation of new bone. Senge et al. utilizes a shock wave source consisting of a spark gap between electrodes within a container of water. An electrical condenser connected to the electrodes releases its energy over a very short period of time, and an arc arises between the electrodes of the spark gap device which vaporizes water surrounding the spark""s path, establishing a plasma-like state. The result is an explosion-like vaporization of the water which produces an electro-hydraulic shock wave that spreads out in a circular fashion. A metallic, ellipsoid-shaped structure surrounds a rear portion of the spark gap, opposite the patient, to produce a known focal point for positioning within the patient""s pathological bone site. This device also requires that the patient be submerged in the water.
Additionally, U.S. Pat. No. 4,979,501 to Valchanov et al., issued on Dec. 25, 1990, teaches a method and apparatus for treating both pathologies with shock or xe2x80x9cimpactxe2x80x9d waves for correction of delayed bone consolidation and bone deformations. The method disclosed in Valchanov et al. comprises the step s of anesthetizing the patient, fixing the limb affected with the pathological bone condition, centering the pathological site of the bone on the shock wave focal point, treating the affected bone site once or consecutively, with 300 to 6000 impacts having a frequency of 0.4-4.0 per second with a pulse duration of 0.5 to 4.0 microseconds for a period of 10-120 minutes, and subsequently immobilizing the limb for a period from 15 to 90 days. The impact wave generating device disclosed by Valchanov et al. generally consists of a vessel which contains a transmitting medium or acoustic liquid such as water contained therein. At a bottom portion of the vessel are opposed electrodes which are adapted to produce a shock across the gap. Therefore, the patient is not submerged for treatment.
Other references teach the treatment of bone pathologies utilizing shock wave therapy in combination with imaging means for localizing the pathology during treatment. Those references include U.S. Pat. Nos. 5,284,144, 5,327,890, 5,393,296, 5,409,446, and 5,419,327. Finally, if the number and magnitude of the shock wave pulses are sufficient, the shock wave treatment may disintegrate a kidney stone. For example, U.S. Pat. No. 4,896,673 to Rose et al., teaches a method and apparatus utilizing focused shock wave treatment of kidney stones in combination with localization using ultrasound or x-ray imaging.
Still other devices utilize transducers for producing ultrasonic waves for therapy of soft tissue. For example, U.S. Pat. No. 5,316,000 to Chapelon et al. teaches an array of composite piezoelectric transducers for making an acoustic or ultrasonic therapy device for use in the treatment of varicose veins. Similarly, U.S. Pat. No. 5,458,130 to Kaufman et al. also purports to therapeutically treat soft tissue such as cartilage, ligament, and tendons using a piezoelectric transducer excited by a composite sine-wave signal with a magnitude as may be prescribed by a physician. Thus, past methods for treating soft tissue surrounding bone utilized a transducer for the generation-of ultrasonic waves for wave propagation into the pathological site within the soft tissue area. Furthermore, as described by Senge et al., clinicians traditionally implemented shock wave therapy for the treatment of bone.
A recent study, reported in xe2x80x9cDamage Spinal Cord Found to Have Great Potential for Nerve Regrowth,xe2x80x9d Case Western Reserve University Press Release, Jul. 15, 1999, describes finding of the capacity for nerve fiber regeneration from transplanted adult nerve cells in adult spinal cords with large lesions. This study implicates molecules in scar tissue at the injury site as the major obstacle to spinal cord regeneration. In the study, sensory nerve cells were transplanted from adult, transgenic mice into the damaged spinal cord of rats, beyond the direct site of the injury. According to current theory, xe2x80x9cboth normal as well as injured adult white matter tracts in the spinal cord are overtly inhibiting because they contain molecules within the myelin sheaths that signal nerve fibers not to grow.xe2x80x9d However, instead of seeing a nerve fiber pathway that was inhibitory for nerve growth, the researchers discovered many axons, so that three months later there was still potential for regeneration away from the site of the injury. At the injury site, the researchers found proteoglycan molecules. These molecules have been correlated with the cessation of axon growth. Further, xe2x80x9cxe2x80x98not only do the regenerating axons stop upon reaching the scar, but they change the shape of their tips and become xe2x80x98dystropicxe2x80x99 with malformed endings. This is the hallmark of regeneration failure.xe2x80x9d The researchers concluded that the study indicates that removing or overcoming molecular obstacles in the scar may allow nerve regeneration in the spinal cord.
Therefore, it is an object of the present invention to provide a rapid, time restricted and effective shock wave therapy treatment for pathological conditions that benefit from such treatment. These conditions include, e.g. plantar warts, deep bone bruises, prostate cancer, spinal cord injuries and incontinence. Other objects and features of the present invention will be more readily understood from the following description of the invention.
This invention relates to methods for medical treatment of pathological conditions. More particularly, the invention relates to methods for using acoustic shock waves to treat a variety of pathological conditions such as plantar warts, deep bone bruises, prostate cancer, benign prostatic hypertrophy, incontinence and the treatment of spinal cord injuries, including the reduction or removal of scar tissue lo aid in spinal cord regrowth. In particular, this invention may be used to remove or reduce scar tissue in the spinal cord, thereby permitting nerve generation, and may be used in conjunction with therapy described above for spinal cord injury.
This invention relates to a method of treating a pathological condition by applying a sufficient number of acoustic shock waves to the site of a pathological condition to induce or accelerate healing in a patient in need thereof. Applying the acoustic shock waves involves generating about 400 to about 3000 acoustic shock waves by applying a voltage potential across a spark gap of a spark gap generator ranging from about 14 kV to about 28 kV to generate each shock wave. The acoustic shock waves may be applied either in a single treatment or in multiple treatments.
In a particular embodiment, the pathological condition is treated by locating a site or suspected site of the pathological condition in a patient in need thereof, generating acoustic shock waves, focusing the acoustic shock waves on the located site, and applying a sufficient number of acoustic shock waves to the located site to induce or accelerate healing. Generating the acoustic shock waves involves generating about 400 to about 3000 acoustic shock waves by applying a voltage potential across a spark gap of a spark gap generator ranging from about 14 kV to about 28 kV to generate each shock wave.
The pathological conditions treated may include deep bone bruises, scar tissue in the spinal cord, incontinence, plantar warts, prostate cancer, or benign prostatic hypertrophy.
The method according to particular embodiments of the invention may utilize physical palpation, X-ray image intensification, CT direction, or ultrasonography precisely to locate the pathological site. Once the site is located, the inventive method may utilize an ellipsoid reflector or focusing lens specifically to direct the acoustic shock waves to the impact (treatment) site.